A cyberattack by an "Islamist group" knocked a French television network off the air on Wednesday night, the broadcaster's director said.
TV 5 Monde said that 11 of its channels, websites and social media pages were hacked at around 10 p.m. local time (4 p.m. ET). The network's website featured a maintenance message as of early Wednesday morning.
"We are no longer able to broadcast any of our channels," the network said in an initial statement. "Our websites and social media sites are no longer under our control."
In a YouTube video, TV5Monde Director General Yves Bigot called it "an extremely powerful cyberattack."
After regaining control of its Facebook page, the network posted a brief message saying that: "This Wednesday, our network, our websites, antennas and social media were 'hacked by an Islamist group'" and that teams were working to restore service.
TV5Monde's statement did not blame any specific Islamist group. Global security firm and NBC News consultant Flashpoint Intelligence said a group called CyberCaliphate had claimed responsibility.
Hackers going by the same name and claiming to be affiliated with ISIS briefly gained control of the social media accounts belonging to the U.S. military's Central Command in January and Newsweek magazine the following month.
French Prime Minister Manuel Valls called the attack an “unacceptable infringement on freedom of speech,” expressing his “total support” for the editorial staff in a Twitter message.
Culture and Communications Minister Fleur Pellerin also expressed solidarity with the network, saying on Twitter they were “victims of a true terrorist attack.”
Evan Kohlmann, an analyst for Flashpoint Intelligence, said that CyberCaliphate had no proven link to ISIS or any other similar group.
"Attacks such as these, which may appear to be spectacular in nature, are a demonstration more of the weak security measures in place at TV5Monde than a demonstration of a capable and competent hacker operation," he added.
France is one of several European countries part of a U.S.-led task force conducting airstrikes against ISIS in Iraq.
Hackers launched a wave of cyberattacks against France after a deadly rampage by Islamic extremists in January that targeted the Paris offices of satirical newspaper Charlie Hebdo. The string of violent attacks left 17 dead. French security forces killed the three gunmen in two separate raids three days after the attacks began.
NBC News' Katie Wong and Cassandra Vinograd contributed to this report.